200 



BULLETIN 93^ UNITED STATES NATIONAL MUSEUM. 



of ATliicli is large. There is a group of small spines aboA^e the lower 

 angle, as in other forms of the species. The third cirrus has very 

 few irregular spinules situated as in figure 61&. The posterior cirri 

 have three pairs of spines on the segments, the lower pair very 

 minute, or sometimes wanting. 



This form differs from that of northern Asiatic waters by the 

 longer basal margin and fhier external sculpture of the scutum, 

 the smooth parietes, and some reduction in the spines of the later 

 cirri. "VVliether these differential features will hold good when 

 the Japanese barnacle fauna is studied from adequate materials 

 remains to be determined. The characters are A'ariable in B. hes- 

 perius. However, it has been thought desirable to signalize by 



Fig. 63. — Balanus iiEsrEuius nipponensis. scutum and 



TERGUM OF THE TYPE. 



name the presence of a modified form of the species in the much 

 warmer waters of Jax^an. 



METABALANUS, new subgenus. 



Parietes and basis not porous; radii Avanting; scutum having a 

 very Aveak articular and no adductor ridge; tergum Avith a ratlier 

 long spur and no external furrow. Third cirri like the second, 

 armed with densely spinose areas and no small spinules. 



Type. — Balanus hoeldanus. 



The single species composing this group Avas formerly placed 

 by me in Hoek's section G of Balanus. It has been enumerated by 

 Doctor Hoek in his genus Hexelasma. The form of the mandible, 

 the ribbed interior of the wall, the overhanging lower edge of the 

 sheath, the long spur of the tergum, and especially the form and 

 chfetotaxy of the third cirri are all Balanid characters and make 

 it certain that the species is not a Hexelasma. Not having the 

 specimens at hand, I have been unable to examine the labrum, but 

 the description of the cirri is amplified beloAV from the slide mounted 

 Avhen I described the species. Whether the absence of radii is suffi- 

 cient to= distinguish Metabalanus from Chirona is someAvhat doubtful. 



